This is a free sample COM add-in (ready to install and use) that adds a number of useful features to Microsoft Excel, including advanced options for Excel styles, merging cells, aligning text and special paste options.
The add-in is based on the advanced Add-in Express technology and is designed to show you how to create add-ins, how to manage add-in's toolbars and controls, and how to access Excel objects.
The add-in contains a full source code in VB, C# and supports Excel 2000, 2002 (XP), 2003 and Excel 2007.